Demonstrators take part in anti-Putin rally in the central Arbat area in Moscow, on March 10, 2012. (NATALIA KOLESNIKOVA/AFP/Getty Images)

Thousands of Russians took part in protests today against Vladimir Putin's victory in last week's presidential election, the BBC reported.

"These authorities are illegitimate," organizer Vladimir Ryzhkov told the crowd on Moscow's central Novy Arbat. "The same people are in power, the same people who took away our right to choose, the same people who destroyed freedom of speech and political competition.

"We will continue to demand deep political reforms and new elections."

Estimates of the turnout varied, according to the Moscow Times, with police saying 10,000 protesters were present and organizers giving figures between 25,000 and 50,000.

The crowd was much smaller than those at opposition protests in December, the BBC said. Then, tens of thousands of people took part in demonstrations claiming that parliamentary elections won by Putin's United Russia party were rigged.

"Before [Putin's] inauguration, we need a million people to turn out on the street," Sergei Udaltsov, the leader of the opposition Left Front, told the crowd. He called on protesters to gather every week in Moscow's Pushkin Square ahead of the inauguration on May 1, Russia's official RIA Novosti news agency reported.

Udaltsov and a handful of his supporters were later arrested for attempting to march on Pushkin Square, which was blocked off by police, according to the Moscow Times.

Police and military vehicles were lined up on surrounding streets, the BBC reported, while at least two helicopters monitored the rally from above, the Guardian said. No significant clashes between protesters and police were reported, however.

According to the BBC's Steve Rosenburg, the smaller crowds are a sign that Russia's protest movement may finally be running out of steam. "The lower turnout shows how hard it will be for the opposition to maintain its momentum following Vladimir Putin's election win," he said, especially as other world leaders – including US President Barack Obama – recognize his victory.